1. Field of the Invention
The present invention relates to a semiconductor device, and, more particularly relates to a semiconductor device that prevents an internal power supply voltage from exceeding a tolerance value.
2. Description of Related Art
In semiconductor devices such as a DRAM (Dynamic Random Access Memory) and a FLASH memory, a boosting circuit is used for generating an internal power supply voltage from an external power supply voltage (see, for example, Japanese Patent Application Laid-open No. 2008-79493). The internal power supply voltage generated by the boosting circuit is supplied to internal circuits of the semiconductor device.
The boosting circuit is a circuit that performs a function of pulling up (boosting) the internal power supply voltage at clock cycles. A voltage level of the internal power supply voltage gradually drops due to consumption of electric charge by the internal circuits. However, even if the voltage level drops, it is pulled up by the boosting circuit. Consequently, on average, a constant voltage level is maintained.
A pull-up range (boosting range) of the internal power supply voltage by the boosting circuit depends on the external power supply voltage. That is, the higher the external power supply voltage, the larger the boosting range, and the lower the external power supply voltage, the smaller the boosting range.